Methods of utilizing waste waters produced by water purification processing

ABSTRACT

The invention relates to disposing of unwanted waste waters produced from purifying water. The methods of the present invention include applying waste water containing 0.15% by weight of the salts of Na, K, Ca, Mg, Fe, Cl, SO 4 , and CO 3  and mixtures thereof to soil to control dust, effect soil stabilization, seal ponds, inhibit root rot, and irrigate soil. The invention also relates to the utilization of waste waters within cooling towers and for laundry applications.

RELATED APPLICATIONS

[0001] This application is a continuation application of pending U.S.Aapplication Ser. No. 09/849,453 filed on May 4, 2001, which is in turn,a continuation-in-part application of U.S.A application Ser. No.09/565,735 filed on May 5, 2000, now U.S. Pat. No. 6,374,539 issued Apr.23, 2002, which is in turn, a continuation-in-part application of U.S.Aapplication Ser. No. 09/110,789 filed on Jul. 6, 1998, now U.S. Pat. No.6,071,411 issued Jun. 6, 2000.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to methods for economic utilizationof waste waters produced from water purification processing.

[0003] Water purification typically produces a first effluent ofrelatively “clean water” and a second effluent of “waste water” whichinclude unwanted contaminates. The softening of hard water by theremoval of calcium and magnesium is required for both industrial andhousehold use. Known water softening processes proceed either by way ofion-exchange, membrane softening or precipitation. In the ion-exchangeprocesses, the calcium (Ca²⁺) and magnesium (Mg²⁺) ions are exchangedfor sodium (Na⁺) and regeneration of the ion-exchange resin is achievedwith a large excess of NaCl. This processes creates a regenerationeffluent being a relatively concentrated aqueous solution of sodium,calcium and magnesium chlorides which has to be discarded. Consequently,by this method, considerable amounts of sodium, calcium and magnesiumsalts in solution must be disposed of.

[0004] Alternatively, it is possible to use weak acid resins whichexchange hydrogen (H⁺) for calcium (Ca²⁺) and magnesium (Mg²⁺), and toregenerate the spent resins with a mineral acid. While this methodcreates less waste water, it is more expensive and yields relativelyacidic soft water which is corrosive. Meanwhile, membrane softeningconcentrates the calcium, magnesium salts and salts of other divalentions to produce waste waters which require costly disposal.

[0005] The precipitation process has traditionally been carried out bythe “lime soda” process in which lime is added to hard water to convertwater soluble calcium bicarbonate into water insoluble calciumcarbonate. This process also results in waste water which is difficultto filter and requires cumbersome treatment.

[0006] My previously issued patent, U.S. Pat. No. 5,300,123 (which isincorporated herein by reference), relates to the purification of impuresolid salts. Even this process produces salty waste water which must bedisposed of.

[0007] The disposal of waste water has become an expensive problem forsociety. For example, approximately 1.61 billion gallons of waste watercontaining approximately 800,000 tons of mixed sodium, calcium,magnesium chlorides and sulfates is produced from water treatmentoperations and oil fields in the state of California alone. This wastewater must be disposed of, costing the state of California millions ofdollars each year. Meanwhile, the disposal of waste water has becomeeven more problematic in other parts of the world. As a result, billionsof dollars are spent each year toward efforts to dispose of wastewaters. Accordingly, it would be highly advantageous to provide improvedmethods of disposing of salty waste waters. It would even be moreadvantageous to provide methods of utilizing salty waste waters whichprovide a benefit to society, instead of simply disposing of theunwanted waste waters.

[0008] Wind erosion of soil is also significant problem throughout theworld. Due to small particle size and poor cohesion, finely divided soilis sensitive to the influence of wind. Such finely divided soil is foundin agricultural lands, dunes, lake beds, construction sites and roadsunder construction. Erosion by wind causes the drifting of masses ofsoil in the form of dust. The erosion by wind causes the inconvenienceof dust formation and the loss of valuable matter such as seed,fertilizer and plantlets. Dust storms are a danger to traffic and ahealth risk to persons located in the vicinity.

[0009] Moreover, the effects of wind erosion on soil can be enhanced bythe influence of the sun and rain. The sun causes the evaporization ofmoisture from soil thereby reducing the cohesion of finely divided soil.Erosion of the soil by rain is caused by rain washing away soil. This isa particular problem when agricultural soil is washed away, damagingplant life and making the soil unusable for agricultural purposes.Further, due to the influence of erosion by rain, the unprotected slopesof ditches, channels, dunes and roads may collapse or be washed away.

[0010] Therefore, it is extremely important to prevent the effects ofthe sun, wind and water in eroding soil. As used herein, soilstabilization refers to the treatment of soils with chemicals to offsetthe tendencies of soils to be sensitive to small changes in the types ofions in the soil moisture as they effect the plasticity of the soil. Forexample, swelled clays, those with layers of “bound” water molecules,are more susceptible to movement under load. Soil stabilization ofswelled clays can be effected by altering the types and/or amounts ofions in the soil mixture.

[0011] It has been proposed to prevent the shift, drift and erosion ofsoil by treating the surface layers of the soil with water dispersiblehigh polymeric substances of a natural or synthetic nature. Examples ofthese high polymeric substances include starch ethers, hydrolyzepolyacrylonitril, polyvinyl alcohol and carboxymethyl cellulose. U.S.Pat. No. 3,077,054 discloses the use of polyvinyl acetate as ananti-erosion agent. U.S. Pat. No. 3,224,867 teaches the conditioning ofsoil with mono starch phosphate. U.S. Pat. No. 5,125,770 teachestreating the soil with a pre-gelatinized starch and a surfactantcompound. Furthermore, it has been known to treat dirt roads withrelatively pure solid sodium chloride (NaCl), calcium chloride (CaCl₂),and mixtures of the two.

[0012] There are several drawbacks with the aforementioned soil treatingcompounds. The polymers mentioned have a relatively high price and havepotentially harmful environmental properties. In addition, the starchethers have proved sensitive to washing out by rain water. As a result,their effectiveness as an anti-erosion agent is severely limited.

[0013] An additional problem encountered throughout the world involvesfungus. There are millions of acres of land in California, Arizona, NewMexico, Texas and the Sonora and Sinaloa areas of Mexico where cropproduction is almost impossible due to fungus which attack virtually alldicotyledonous plants of which there are more than 2,000 species. Theseinclude cotton, alfalfa and citrus trees. The lack of productivity isdue to excessive calcium carbonate in the soil which minimizes swellingto the point that carbon dioxide from decaying humus concentrates tomore than about 3.2% CO₃, where fungus thrives. These fungus, primarilyPhytomatotrichum omnivorim (Shear) Duggar, have three stages ofdevelopment called the mycelium, conidium and scelerotia. The firststage, referred to as mycelium, involves the development of a finefilament which branches out throughout the soil and forms a tight webaround plant roots. After the filament reaches the soil surface, a whitemat forms on the surface, referred to as conidium. When mature, themycelium develops multicellular bodies called scelerotia which canextend to a depth of up to twelve feet into the soil.

[0014] About 1970, it was discovered that the addition of sodium to soiloffset the excess calcium in the soil. This increased the soilpermeability and avoided the build-up of carbon dioxide that permits theroot rot to flourish. Sodium chloride has been applied where the soildrains readily and the excess chloride and sodium are leached away byrainfall or irrigation. Meanwhile, sodium sulfate is preferablebecause 1) the sulfate supplies the nutrient sulfur, 2) the sulfatecombines with calcium to form gypsum and gypsum soils typically do notsupport root rot, 3) gypsum buffers excess sodium assisting its leachingfrom the soil, and 4) there is no additional chloride residue which canleach into the water table. Unfortunately, sodium sulfate has alwaysbeen too costly to be used to treat soil for farming. Recently, it hasbeen suggested that solid mixtures of salts removed from water softeningprocesses can be used to control root rot. However, salts removed fromwater softening are still relatively expensive and the process ofutilizing salts recovered from waste water has not been adopted withinthe agricultural community.

[0015] Still an additional problem encountered in agriculture is thatsoil is often too high in sodium and/or too high in salinity. Farmlandand irrigation water is often unacceptably high in sodium. Irrigationwaters containing high amounts of sodium salts versus calcium and/ormagnesium salts can create a buildup of sodium in the soil. This excesssoil results in the dispersion of soil colloidal particles and anincrease in soil pH. The dispersion of colloidal particles causes thesoil to become hard and compact when dry and increasingly resistant towater infiltration and percolation. The sodium rich soil also becomesresistant to water penetration due to soil swelling when wet.

[0016] The total salinity of soil and irrigation water is also ofconcern. Salinity refers to the total salts within the water, with thesignificant positive ions (cations) in salinity being calcium, magnesiumand sodium and the significant negative ions (anions) being chloride,sulfate and bicarbonate. All irrigation water contains some dissolvedsalts. When soil has a high content of dissolved salts, or theirrigation waters have sufficient salts to increase the salinity of thesoil, the soil has the tendency to hold the water instead of releasingthe water for absorption by plant roots by osmotic pressure. Even if thesoil contains plenty of moisture, plants will wilt because they cannotabsorb necessary water.

[0017] Ironically, though there is an overabundance of waste waters thatare contaminated with the salts of Na, K, Ca, Mg, Fe, Cl, SO₄, and CO₃that, as discussed above, is extraordinarily expense to dispose of,millions of dollars are spent each year on salts such as sodium chloridefor deicing highways. It would thus be advantageous if the salts inwaste water could be used for deicing highways.

[0018] It would also be highly desirable to provide a method fortreating soil that is of low cost and utilizes a material or compoundwhich is readily available. It would be even more advantageous if saltywaste waters could be used to treat soil to control dust and effect soilstabilization.

[0019] It would also be desirable to provide a method inhibiting rootrot in soil.

[0020] Moreover, it would be desirable to provide a method ofmaintaining the proper salinity levels and salinity equilibrium in soilto enhance the agricultural properties of soil.

[0021] Finally, it would be desirable if all of the aforementionedobjectives could be accomplished while overcoming an expensive andproblematic concern facing this country and the rest of the world, thedisposal of waste waters.

SUMMARY OF THE INVENTION

[0022] Briefly, in accordance with the invention, I provide methods foreconomically and efficiently utilizing the waste waters produced bywater purification and particularly those produced from oil and gaswells, and irrigation drainage. To this end, my invention is sosuccessful, the effluents produced from water purification should nolonger be referred to as “waste” waters at all.

[0023] I have learned that by applying the waste water from waterpurification, such as water softening processes, upon soil provides anexcellent means for controlling dust from wind blown soil and foreffecting soil stabilization. More particularly, I have learned that thedirect application of the salty waste waters from water purification andwater softening processes is effective in treating industrial clays;controlling dust; stabilizing load bearing soils such as foundations,road beds, etc. I have also learned that the direct application of wastewaters to soil can be applied in similar manner to seal soil surfacesfor pond sealing.

[0024] The waste waters of the present invention are any waters whichare produced as a result of the purification of water, and particularlypurified “oil field produced waters” and irrigation drainage, whichresults in a first effluent of clean water and a second effluent of awaste water, which typically must be disposed of. As defined herein,clean water refers to water which has been treated by one or severalmethods for public or industrial use. For example, in the drinking waterindustry, clean water is the final delivered water. Typical waterpurification processes and water softening processes of the presentinvention include reverse osmosis, electro dialysis, distillation,evaporation, ion exchange and lime softening. These processes createwaste water having various levels of salt content. For the purposes ofthis invention, I define “waste water” as water containing about 0.15%or more by weight of the salts of Na, K, Ca, Mg, Fe, Cl, SO₄, and CO₃ ora combination thereof. Prior to the practice of my invention, the wastewater from any of these processes was expensive to dispose of.

[0025] I have also learned that waste waters produced from waterpurification, particularly those high in calcium, magnesium, iron andsulfates, can also be used to control dust and to irrigate farm land, oras additive to irrigation waters, where the soil has a high sodiumcontent.

[0026] In addition, I have discovered that, conversely, waste waterswhich have a high sodium content are particularly suitable for soilstabilization, pond sealing and treating root rot. These high sodiumwaste waters are also suitable for use in cooling towers and laundryapplications.

[0027] Moreover, I have discovered that waste waters can be processed tocreate both solid and aqueous mixtures which can be applied to roads andhighways for deicing and for reducing the tendency of water to form intoice on roads and highways.

[0028] The waste water may be applied to the soil by any means commonlyknown in the art. For example, the waste water may be applied byspraying from the back of a truck or other type of construction or farmequipment. In addition, the waste water may be applied to the soil byslow moving aircraft.

[0029] Accordingly, it is an object of the invention to provide costeffective means of disposing of waste water produced from thepurification of water. To this end, it is a principal object of theinvention to provide new methods for utilizing waste water produced fromwater purification.

[0030] It is an additional object of the present invention to providenew methods for stabilizing soil and controlling dust from soil.

[0031] It is still another object of the present invention to providenew methods for treating soil to reduce root rot in soil to providepreviously unuseable land for farming.

[0032] Furthermore, it is an object of the present invention to providenew methods for irrigating soil to provide proper sodium and salinitylevels for agriculture.

[0033] In addition, it is an object of the present invention to provideto methods of for providing solid and liquid mixtures for deicing roadsand highways.

[0034] These and other, further and more specific objects and advantagesof the invention will be apparent to those skilled in the art from thefollowing detailed description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a flow chart of the preferred method of the invention;

[0036]FIG. 2 is a flow chart of another preferred method of theinvention;

[0037]FIG. 3 is a flow chart of still another preferred method of theinvention;

[0038]FIG. 4 is a flow chart of a preferred method of the presentinvention including evaporation to produce substantially solid sodiumchloride;

[0039]FIG. 5 is a flow chart illustrating a method of the presentinvention for applying softened waters for laundries, root rot, coolingtowers, pond sealing and soil stabilization, and for applying wastewaters for dust control and agriculture;

[0040]FIG. 6 is a flow chart illustrating a practice of the presentinvention including membrane softening to produce waste water forapplication to control dust, control soil salinity or irrigate soil;

[0041]FIG. 7 is a flow chart illustrating a practice of the presentinvention including water purification to produce waste water forapplication to control dust and irrigate soil;

[0042]FIG. 8 is a chart illustrating the sodium absorption ratio (SAR)of irrigation waters; and

[0043]FIG. 9 is a flow chart illustrating a practice of the presentinvention including a closed loop system for treating soil.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] While the present invention is susceptible of embodiment invarious forms, as shown in the drawings, hereinafter will be describedthe presently preferred embodiments of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the invention and it is not intended to limit theinvention to the specific embodiments illustrated.

[0045] Water softening is the removal of the “hardness” from the waterwhich means predominantly removing or altering the calcium and magnesiumions from the water. These calcium and magnesium ions combined withcarbonates, sulfates, oils and fat to create bathtub scum, spotteddishes, gray sheets, etc. In addition, unsoftened water has been foundto cause scaling of industrial water heaters and commercial boilerscausing early substantial energy losses through impaired heat transferand early shutdown for the removal of scale. Several methods foreffecting water softening are known. The best known process forsoftening water is “ion-exchange”. Ion-exchange entails the exchange ofsodium, which is introduced into water, for calcium, magnesium, iron andother divalent mineral ions which are transferred out of the water andinto a resin. When the resin approaches saturation with these hard ions,the resin is regenerated most often with solutions of sodium chlorideleaving an effluent containing 3 to 25% sodium, calcium and magnesiumsalts which must be disposed of. The exact concentration of the effluentdepends on the shop practice and, in particular, on the amount of rinsewater included in the effluent, if any. Less often mineral acids likesulfiric acid or hydrochloric acid are used for water softening andthese also produce effluents. Conversely, reverse water softening alsoinvolves ion exchange in which calcium and magnesium into the water toseparate sodium

[0046] Membrane systems have recently become economically feasible.These systems, such as electro dialysis and reverse osmosis, include theuse of a membrane which also produces a salty effluent. For criticaluses such as electronics, and particularly for use in the manufacture ofcomputer chips, the first product of clean water may be further purifiedby dual bed or mixed bed ion-exchange treatment. This “polishingtreatment” also produces an effluent containing the removed salts.

[0047] Each of these water purifying processes produce a clean watereffluent and a waste water effluent which is expensive and difficult todispose of. Moreover, in U.S. Pat. No. 5,300,123, I disclose a methodfor reducing the soluble and insoluble impurity levels in salt. In thepractice of this invention, salt crystals are initially reduced in sizeby fine grinding the crystal mass. The crystal mass is then added to asubstantially saturated solution of salt and the strain induced in finegrinding process causes them to dissolve in the substantially saturatedsolution to the extent that the solution becomes supersaturated and newpurified crystals form and grow. This dissolving and reforming iscontinued until substantially all of the original finely groundparticles of salt have dissolved and reformed as new purified crystals.The new purified crystals are separated by size from the solution andrinsed, while the fine insoluble impurities which do not growappreciably, if at all, remain in the now impure solution of sodium,calcium and magnesium chlorides, along with minor impurities from theoriginal waste salt.

[0048] I have learned that the waste water produced from waterpurification and water softening processes, and the calcium andmagnesium substantially saturated solution produced in practicing myinvention disclosed in U.S. Pat. No. 5,300,123, can be effectively usedas soil amendments to control dust and effect soil stabilization. Thechemical and physical properties of clays and soils have ion-exchangeproperties which are determined in great part by their contact withwater soluble chemicals. Chemicals having particular influence on thephysical properties of soil are sodium, potassium, calcium and magnesiumbecause these are common cations. The most common anions found in soilsare chloride, sulfate, carbonate and bicarbonate. The concentration, andrelative concentration, of the various dissolved ions determine theactivity of the exchangeable ions attached to soil particles. Thus, itis possible to alter and regulate the behavior of soils by controllingthe ratio and amount of the various ions applied to the soils.

[0049] More particularly, I have found that waste waters having increasesodium or potassium have much greater effectiveness in stabilizing soilsthan the calcium and magnesium salts. Moreover, I have discovered thatwaste waters high in sodium are also effective to control root rot.

[0050] Conversely, I have found that the calcium and magnesium chloridesin waste waters have much greater effectiveness in controlling dust fromwind blown soil than the sodium salts. I have also found that, ingeneral, the calcium and magnesium salts do not noticeably interferewith the sodium chloride's ability to stabilize soils, while the sodiumsalts do not reduce the effectiveness of calcium and magnesium chloridesfor dust control. Moreover, the calcium and magnesium salts areeffective for irrigating farm land, particularly where the sodiumabsorption ration needs to be adjusted.

[0051] For the purposes of this invention, “waste water” is defined asany water containing sufficient salts as to have no acceptable use dueto costs or contamination levels. In general, waste water containingabout 0.15% or more by weight of the salts of Na, K, Ca, Mg, Fe, Cl,SO₄, and CO₃, or combinations thereof are considered as having noacceptable use and must be disposed of.

[0052] With reference to FIG. 1, in a preferred embodiment, water iscollected which is contaminated with salts including Na, K, Ca, Mg, Fe,Cl, SO₄ and CO₃. The contaminated water is purified by any means knownto those skilled in the art, including distillation, reverse osmosis,electrolysis, evaporation, ion exchange, etc. The contaminated water isprocessed to produce a first effluent of relatively clean water which isuseful for agricultural purposes, drinking water, industrial purposes,etc. The processing also produces a second effluent of waste water. Thewaste water is analyzed for hazardous materials to confirm that thewaste water is safe to use. Thereafter, the waste water, comprising anaqueous solution of salts, is analyzed for individual amounts of sodium,calcium, and magnesium and total dissolved solids to determine the bestapplication and the amount of solution to be applied to a particularsoil. The waste water is then applied to soil by spraying from a truck,aircraft or the like to effectively control dust and/or stabilize thesoil. Where the concentration of salts is not enough to meet therequired needs in a single application, several applications of thewaste water may be employed.

[0053] With reference to FIG. 2, in a second preferred embodiment, wateris collected which is contaminated with the salts of Na, Ca, Mg, Fe, Cl,SO₄, and CO₃. The water is then tested to confirm that it is free ofhazardous materials. The contaminated water is then purified by ionexchange. As the name implies, the amount of salts in the effluents doesnot change. However, the cations are exchanged. By this process, a firsteffluent of clean water is produced having an increase in sodium orpotassium. Where the contaminated water originally contained a lowamount of sodium, it is preferred that this water be used for potablewater. Meanwhile, where the contaminated water originally contained highsodium amounts, it is preferred that the clean water effluent be usedfor laundries, boilers, cooling towers, pond sealing and soilstabilization. These applications are typically more tolerant of watershaving high sodium content, as long as the magnesium and calcium contentremains low. These uses are listed in order of suitability as the sodiumincreases. As shown in FIG. 2, the water softening process by ionexchange also produces a waste water having decreased NaCl, KCl, Na(OH)₂or acid, but having an increase in calcium and magnesium. Forapplication of the present invention, this waste water is then appliedto soil by spraying from a truck, aircraft or the like to control dust.

[0054] With reference to FIG. 3, in a fourth preferred embodiment, wateris collected which is contaminated with the salts of Na, K, Ca, Mg, Fe,Cl, SO₄, and CO₃. The water is then tested to confirm that it is free ofhazardous materials. This contaminated water is then purified by amembrane system to remove large molecules. A first effluent of cleanwater having decreased multivalent ions is produced from the membranesoftening process. Where the original sodium content of the contaminatedwater is relatively low, it is preferred that the clean water be usedfor potable water. Where the original sodium content of the contaminatedwater is relatively high, it is preferred that the clean water effluentbe used for laundries, low pressure boilers, cooling towers, pondsealing and soil stabilization. The membrane system also creates a wastewater having significant calcium, magnesium, iron, sulfates, etc. Forapplication of the present invention, it is preferred that this wastewater be applied to soil by spraying from a truck, aircraft, or the liketo effectively control dust.

[0055] As shown in FIG. 4, in a fourth embodiment of my invention, watercontaminated with the salts of Na, K, Ca, Mg, Fe, Cl, SO₄, and CO₃ iscollected. The contaminated water is desalted to produce a firsteffluent of relatively clean water, and a second effluent of wastewater. The second effluent of waste water undergoes furtherevaporization processing to produce a first product of 90% or more NaCl,and a third effluent solution of substantially saturated CaCl₂ andMgCl₂. For practice of the invention, the NaCl is then applied to soilto effect soil stabilization. Meanwhile the third effluent solution ofmixed CaCl₂ and MgCl₂ is applied to soil to effect dust control.

[0056] As would be understood by those skilled in the art, the preferredamount of water and the percentage of salts contained therein to controldust and effect soil stabilization will vary greatly. Factors which willeffect waste water applications include the chemical composition of thesoil, the moisture in the soil, humidity, local rainfall, trafficconditions, etc.

[0057] Since the testing of soil is expensive, it is preferred that thewaste water be applied in several applications. Waste water is appliedand allowed to evaporate. The soil is examined to determine ifsufficient waste water has been applied to control dust or stabilize thesoil. These steps are repeated until sufficient salts have been appliedto control dust or to stabilize the soil.

[0058] The embodiments described above will now be further explained inand by the following examples.

EXAMPLE 1

[0059] Approximately 2.7 miles of road in the Mojave Desert ofCalifornia is treated with waste water containing approximately 12.5%total salts, and in particular, about 1.37% calcium chloride, 0.39%magnesium chloride and 10.7% sodium chloride. After treatment, the roadunderwent periodic truck traffic. Visual comparison of dust produced bytruck traffic is measured against a section of road which has not beentreated. Following a rain, dust starts to be visible from a one miledistance within 2-4 days for the untreated road, while dust starts to bevisible from the one mile distance within 10-20 days for the treatedsection of road.

[0060] Thereafter, waste water applications are increased for a threemonth period. The amount per application is the maximum that the soilwill absorb without turning muddy. Then, the applications are ceased.The road is examined over the next year and found not to exhibit anysignificant dusting. In addition, there is a distinct reduction ofwashboarding.

EXAMPLE 2

[0061] Approximately one mile of dirt road in the Mojave Desert istreated with a mixture of sodium, calcium and magnesium salts.Application of the untreated waste water proves effective for effectingsoil stabilization. Compared to untreated sections of the dirt road, thesoil is found to be more stable and less prone to being spread byrainfall, and is found to be much less prone to washboarding andpotholing.

[0062] With reference to FIG. 5, in a fifth preferred embodiment of thepresent invention, water is collected which is contaminated with thesalts of Na, K, Ca, Mg, Fe, Cl, SO₄, and/or CO₃. The contaminated wateris then tested to determine that it is free of hazardous chemicals, andif the water is determined to sufficiently free of hazardous chemical,the water is purified by water softening, such as by ion exchange. Asshown, ion exchange produces an first effluent of clean water whichtypically has a high sodium content. As explained with reference to FIG.2, where the clean water has a low sodium content such as where theoriginal contaminated water had a low sodium content, the water may beused for potable applications. Meanwhile, where the clean water has ahigh sodium content, the clean water may used for laundry applications,cooling towers, pond sealing and soil stabilization. The clean waterhaving a high sodium content may also be applied to soil to inhibit rootrot. The added sodium counterbalances any excess calcium in the soil toincrease soil permeability and inhibit the buildup of carbon dioxide inthe soil. Without the carbon dioxide in the soil, the root rot funguseither dies, or at least its growth is inhibited.

[0063] Still with reference to FIG. 5, the waste water produced by ionexchange typically has an increased level of calcium and magnesium. Thiswaste water may be applied to soil to control excess soil dusting. Inthe alternative, where the soil at issue requires soil stabilization,pond sealing or root rot control, the waste water undergoes evaporationto produce solid NaCl which can be applied to the soil. Moreover, I havefound that the waste water can be processed through evaporation, or inaccordance with the methods disclosed in my U.S. Pat. No. 5,300,123, toproduce substantially solid sodium salt which can be applied to roads tolower the freezing point of water on the roads. Meanwhile, the wastewater having an increased level of calcium and magnesium can be applieddirectly to the soil, or concentrated through evaporation and thenapplied to soil, for irrigation purposes and for adjusting the soil'ssodium absorption ratio (SAR). In addition, even though the calcium andmagnesium solution is typically aqueous, it can also be applied to roadsand highways to inhibit the formation of ice on the roads as calcium andmagnesium salts also lower the freezing point of water. Thus, any waterpreviously on the road will freeze at a lower temperature once mixedwith the calcium and magnesium solution which has been produced as aresult of evaporating the waste water.

[0064] All irrigated areas suffer from a buildup of sodium. Plantevaprotranspiration and plant growth use about 70 to 90% of theirrigation water and the sodium is concentrated in the remaining 10 to30% of the water. This water must be washed from the roots or plantgrowth suffers. As shown in FIG. 8, the sodium buildup is predicted bythe sodium absorption ratio (SAR) vs. the total of salinity of theirrigation water. To use the chart in FIG. 8, the sodium concentrationis marked on the left side of the nomogram. The calcium plus magnesiumconcentration is then marked on the right side of the nomogram. Drawinga straight line between the two marks identifies the SAR value where theline intersects the sodium adsorption scale. Due to the inverserelationship between the addition of sodium to calcium and magnesium, anincrease in calcium and/or magnesium will actually lower the SAR valueof the irrigation water. With reference again to FIG. 5, by using thewaste waters having a high calcium and magnesium content as irrigationwater reduces the buildup of exchangeable sodium in the soil therebymaintaining the soil in proper sodium equilibrium.

[0065] With reference to FIG. 6, membrane softening also creates a firsteffluent of clean water and a second effluent of waste water. Forpracticing the present invention, the clean water is utilized forpotable applications where the sodium is low, but used for laundry, lowpressure boilers, cooling towers, pond sealing soil stabilization ortreating root rot where the sodium is high. Meanwhile, the waste waterfrom membrane softening typically has significant levels of calcium andmagnesium. As discussed above, instead of simply disposing of thesewaters, it is preferred that these waste waters be used for dust controlor for controlling the sodium level in the soil. As shown in FIG. 6,controlling the level of the sodium in the soil can be accomplished inone of two ways. The waste water can be applied directly to the soil toadjust the SAR, or the waste waters can be used in cooperation with ionexchange water softening processing to reduce the amount of sodium inirrigation waters. These irrigation waters, now lower in sodium, areapplied to the soil to maintain the soil's sodium equilibrium level, orto leach out sodium from the soil to place the soil into a proper sodiumequilibrium level.

[0066] With reference to FIG. 7, for practicing an additional embodimentof the present invention, water that is contaminated with the salts ofNa, K, Ca, Mg, Fe, Cl, SO₄, and CO₃ is desalted by distillation, reverseosmosis, electrodialysis or ion exchange to produce a first effluent ofclean water and a second effluent of waste water. The waste water ispreferably tested to ensure that it is free of hazardous materials. In apreferred practice of the present invention, the water undergoesevaporation to produce a substantially solid mixture and a solutionconcentrate. The substantially solid mixture is comprised primarily ofsodium salts and is thus suitable for use as a soil stabilizer or forinhibiting root rot by directly applying the solid mixture to soil, orby adding the mixture to irrigation water. Moreover, for practicing thepresent invention, the solid mixture of sodium salts is also applied toroads and highways for deicing and for impeding the formation of ice onthe roads and highways.

[0067] Meanwhile, evaporation concentrates the waste water to produce anaqueous concentrate of calcium and magnesium salts. The concentratedsolution is applied to soil to reduce soil dusting or is applied to soilto adjust the soil's sodium adsorption rate. As described with referenceto FIG. 6, the concentrate may be applied directly to soil or may beused to reduce the sodium content in the irrigation water throughadditional ion exchange processing. In the alternative, the concentratedsolution of calcium and magnesium salts is applied to roads and highwaysfor deicing and for impeding the formation of ice on the roads andhighways.

[0068] With reference to FIG. 9, in still an additional embodiment ofthe present invention, a substantially closed loop system is providedfor adjusting the properties of soil. As reflected in FIG. 9, farmerstypically irrigate the soil while simultaneously adding to the soilsignificant levels of potassium chloride, potassium sulfate and ammoniumsulfate as fertilizer. Over time, the addition of these fertilizerstypically introduces substantial salts to the soil which must be leachedout of the soil or drained from the soil such as by using pumps tomaintain the soil at optimal conditions for agriculture. For practicinga preferred method of the present invention, the water drained from thesoil is purified, such as by ion exchange reverse softening. For reversesoftening, a solution of calcium chlorides, magnesium chlorides, and/ormagnesium sulfates is prepared to create a regenerative solution, suchas can be obtained as shown in FIG. 5. The reverse softening processproduces a used regenerate solution having increased sodium but withreduced calcium and magnesium. The regenerate solution preferablyundergoes evaporative processing producing a 90% solid mixture of sodiumsalts which is preferably used for treating root rot or for soilstabilization, depending on the properties of the soil at issue.Meanwhile, the evaporative process also creates a concentrated solutionof calcium and magnesium salts. Where the soil suffers from dusting orrequires adjustment of the soil's sodium adsorption rate, instead ofapplying the 90% solid mixture of sodium salts, this concentratedsolution of calcium and magnesium salts is applied to the soil to reducethese problems. Still with reference to FIG. 9, the ion exchange processalso creates a “clean” water effluent typically low in sodium salts buthigh in calcium and magnesium salts. Where the soil suffers fromproblems such as dust control or an improper sodium adsorption rate, asopposed to root rot or soil stabilization, this clean water effluent canalso be applied to the soil to reduce these problems. The aforementionedprocess, thus, provides a substantially closed loop procedure formaintaining soil at desired equilibrium levels, notwithstanding that thesoil may suffer from wildly divergent chemical problems.

[0069] In addition to the uses for waste waters described above, I havediscovered many additional uses for waste waters and the productsproduced from purifying waste waters.

[0070] Salty Irrigation Drainage

[0071] Irrigation water contains salts and some inorganic fertilizermaterials that are used by plants in varying degrees but rarely, ifever, in their entirety. Plants separate water and nutrients selectivelyfor growth and for temperature regulation by evapo-transpiration. Somewater is evaporated at the soil surface leaving the salts behind. Theremaining water becomes salty, and, if not flushed out of the root zone,reduces the crop yield. The continued pumping of ground water canrecirculate the salts until their concentration makes agricultureuneconomical.

[0072] Where the irrigation water is from a source other than localgroundwater, the downward percolating irrigation water causes the localwater table to rise. When the water table nears the surface, say toabout 6 feet or less, the salty water can migrate upwards reducing cropyield and eventually covering the surface with salts. These onceproductive lands become barren.

[0073] This has been occurring since the first recorded irrigation alongthe Tigris and Euphrates Rivers of about 3000 years ago. Today, tens ofmillions of hectares of once fertile land are no longer productivebecause of salty irrigation drainage.

[0074] We presently mine something more than 250,000,000 tons of saltseach year and this includes great amounts of the salts found in saltyirrigation drainage. Ironically, large amounts of some of the saltsbeing mined are used in agriculture.

[0075] The recovery of some or all of these salts, with or without someof the waters, becomes increasingly necessary and desirable.

[0076] Waste-waters high in sulfate are also produced in geothermaloperation and from other natural sources. While this discussion isstated mostly in terms of irrigation drainage, persons skilled in theart will recognize that the work herein described is applicable to theseother sulfate waste or by-product waters.

[0077] Irrigation drainage is different from salty wastewaters, whichresult from industrial use of sodium chloride and other chloride salts.(Reference patent and patent pending. The ocean and the salt depositsfrom the drying of ocean waters and most inland lakes collecting surfacewaters from rainfall are high in the negatively charged anion, chlorine(Cl) as compared with the sulfate anion (SO₄) Ratios of Cl ion/SO₄ ionare;

[0078] 8.45 Cl/1 SO₄—Great Salt Lake of Utah

[0079] 7.1/1— Seawater

[0080] 1.3/1— Salton Sea; This irrigation drainage includes the leachingof chloride salts from irrigated land which was once the floor of anocean bay.

[0081] The heavy agricultural use of sulfate soil amendments like gypsumand of fertilizers like ammonium and potassium sulfates reverses theratio for irrigation drainage and some ground water. The only chloridefertilizer used in significant tonnage is potassium chloride, commonlycalled potash.

[0082] Agricultural Drainage in the San Joaquin Valley of Californiaexhibits this reversal with SO₄/Cl ratios varying from 2.2/1 up to ashigh as 27/1.

[0083] Different technology is required and different salt products maybe recovered so as to add to the uses for salts recovered from wastes.

[0084] The alkaline nature of these waters also allows higher carbonatecontent.

[0085] The different products to be recovered form these differentwaters allow a wide expansion of the beneficial uses for salts recoveredfrom wastes.

[0086] Thus, some of the methods for recovering products from irrigationdrainage differ from those used for recovering salts from chlorides typewastes. Additionally, the products themselves vary according to theamounts of each salt in the wastes, and of course the carbonate andsulfate products increases the number of uses of salts recovered fromwastes. Each new use of a salt product cuts the waste volume. The usescan be expanded until the waste volume becomes almost negligible. Onefactor contributing to the expansion of uses is the high volume ofirrigation drainage waters, their widespread occurrence, and their rapidgrowth in their volume that endangers sustainable agriculture.

[0087] Local Recycling of much of the recovered salts back to the soilreduces the need for mining and also reduces the energy use in themine-to-market haul.

[0088] Recovery of salts near to markets so lowers their distributioncost as to make new uses economical and old uses less costly. Thereduction in the cost of disposal of a waste plus the reduced energy usein transportation of the salts are added benefits.

[0089] Dramatically lower costs expand the economical uses andcontribute to the overall benefits of the economy. There are many usesfor salts that do not require the purity of the grades of commerce nowin general use. This allows the preparation of usable grades at minimumcost and the even lower costs again serve to broaden the fields ofeconomic use.

[0090] How Salts Work With Soils. Clays are the original ion-exchangemedia and it was a study of soils that started the present day art andscience of ion exchange. All soils have a clay component and thephysical characteristics of clay changes very much as the type andamount of the cations Ca, Mg, and Na, vary. Further, the properties alsovary according to the ratio of the dominant anions, chlorine andsulfate. It takes a lot of salt to satisfy the ion exchange requirementsof soils. The top one foot of naturally packed soil weighs about 100pounds per cubic foot, 4,328,000 lbs., or 2164 tons/acre. Though theweight percentage of these salts is small in relation to the weight ofthe soil, the amount of the salts is large because the weight of thesoil is so very large. Therefore any attempt to alter the balance of theions that control the clays requires large amounts of salt.

[0091] Example—This is demonstrated by California's use of somethingover 300,000 tons of calcium sulfate from mines as a soil amendment eachyear for mitigating the effects on soils caused by sodium brought to thefields by irrigation water. The irrigation waters brought into the SanJoaquin Valley contain approximately 1.6 million tons of chloride saltsper year. The Salton Sea receives about 4 million tons of salts per yearfrom all forms of runoff, of which 60% or more is brought in with theapproximately 3 million acre feet of Colorado River Water used yearlyfor irrigation.

[0092] Sustainable agriculture in California requires the removal of aminimum of about 5-6 million tons of salts each year from saltyirrigation drainage whether from runoff or from a rising salty watertable. Though some salts may be exported, to avoid the dollar andenvironmental costs of stockpiling waste, most salts find domestic uses.I have found that large tonnages of sulfate salts can be recovered foruse locally for return to the cultivated fields and for relatedagricultural uses such as stabilization of farm roads, reduced dusting,and use for storage of ambient energy, solar energy, and waste heat fromfossil fuel burning and the use of electricity.

[0093] Direct Use of Irrigation Drainage

[0094] Irrigation drainage most often carries an appreciable amount ofcalcium as the carbonate. When a sulfur dioxide containing gas isbrought in direst contact with such irrigation drainage the sulfurdioxide is reduced by reaction with the calcium carbonate to formgypsum. The gypsum, after washing, is used to replace some of the gypsumnow mined for use, for example, as a soil amendment in agriculture andfor producing wallboard.

[0095] When irrigation drainage is mixed with salty water produced fromoil or gas wells where the formation has an oceanic origin, the calciumchloride in the produced waters reacts with the sulfate in theirrigation waters to produce gypsum. There is a corresponding decreasein salts content of the blended waters and the gypsum can be used asnoted above.

[0096] Products from Irrigation Drainage and Other Sulfate Type WasteWaters

[0097] Calcium Carbonate—As evaporation progresses, the first saltproduct to separate is calcium carbonate, a mineral that is mined by thetens of millions of tons/year.

[0098] The calcium carbonate recovered from irrigation drainage hasproperties that, for many uses, render it much superior to materialmined from the typically very large and hard deposits. For limestone,most uses involving chemical reactions work best and faster as thesurface area is increased and fresh surfaces are produced by sizereduction.

[0099] Production of chemically active limestone, as differentiated fromconstruction uses for aggregate or blocks where the desired property ismostly mechanical, takes much energy in the form of stripping ofoverburden, drilling, blasting, grinding, and restoration of thesurfaces as required for mine reclamation. Thus it is desirable toreduce the great expenditures of money and energy for mining whilereducing the problem of what to do with salty irrigation drainage.

[0100] By contrast, during solar evaporation the calcium carbonatecrystals are formed so small that, in still waters, they actually float.After sinking due to continued growth and/or water turbulence, theapparent growth is more by agglomeration of small crystals than bycontinued growth of individual crystals. Further, both the smallcrystals and the agglomerations are weak as compared with naturaldeposits and may be easily ground to give the large amounts of freshlyfractured surfaces most desirable for chemical reactions.

[0101] Experimental—Irrigation Drainage from the Salton Sea

[0102] The Salton Sea in Southeast California receives irrigation anddomestic drainage containing large amounts of mixed salts includingnitrates. Evaporation has concentrated the salts to 25% higher thanseawater. Much of the Sea is shallow and warm weather fosters algaeblooms that result in large kills of fish and wildfowl. Reversal ofthese conditions requires the removal of salts at some rate greater thanthe inflow. Much of the salt content is beneficial to agriculture andshould be returned to the areas of farmland that needs them. Huge needsfor common salts are accumulating because the present prices for thesalts are too high.

[0103] The Imperial Valley area in which the Salton Sea lies was oncepart of the Sea of Cortez. It was cut off by the spreading delta of theColorado River and dried up to become a large depression. Flooding ofthe lowest part started with a canal breaking in 1908. Irrigationdrainage and other inflow has increased the surface area of the SaltonSea (SS) to 381 square miles (98,700 hectares) at an elevation of 227feet (69 meters) below sea level (1). Irrigated land on the periphery ofthe depression receives 3 million acre feet (3.7×10⁹ cubic meters)/yearof Colorado River Water with a salinity varying around 700 PPM TDS. TheSS itself receives 1.3 million acre feet (1.6×10⁹ cubic meters) ofirrigation drainage and other runoff. The incoming salts concentrationis about 4400 PPM TDS for an inflow of over 3.6 million metric tons ofmixed salts per year. Evaporation has raised the levels of salts to44,000 PPM TDS of which about 900 PPM is NO₃. The nutrient content ofthe water is so high that warm wether triggers algae blooms, usually inshallow areas, that deplete the oxygen causing massive fish kills. Largenumbers of wildfowl also perish, possibly because they eat thedecomposing fish. No evidence of excessive levels of pesticides or ofselenium above 1 PPB has yet been recorded. Work is underway to save thewildfowl and fish habitat and to return the Salton Sea to its formerstatus as a prime recreational area. Government funding probably willinclude only provisions for “landfilling” the recovered mixed salts.

[0104] Tests were run so as to duplicate, on a reduced scale, thetypical solar practice of two or more evaporation stages, in series, toget best evaporation efficiency. Evaporation was carried out induplicate pans 33 cm×63 cm×10 cm deep, lined with polyethylene film.Daily ambient highs were 38-42*C. and night lows were 15* to 17*C. less.Daytime relative humidity was 15 to 25%. The specific gravity (sg) ofthe Salton Sea water was 1.03 as measured by hydrometer.

[0105] On the second day of evaporation (sg 1.047) white flakes wereforming with many floating on the brine surface. By morning of the thirdday, at (sg 1.057), the flakes formed an almost continuous covering. Theevaporation rate varied between 0.9 and 1.2 centimeters per day untilthe specific gravity was at 1.145 and the floating crystals, nowincluding other salts, formed a thick continuous (surface) skin thathindered evaporation.

[0106] Before the skin formation the brine temperature daily highs werein the range of 22 to 30 C. After a continuous skin formed on thesurface the brine temperatures were as high as 48 C. At this point, sg1.145, about 75% of the precipitate in pan ‘B’ was taken for analysisand allowed to drain but was not washed. It analyzed 17.8% Ca, 0.8% Mg,0.51% sulfate, and 0.18% potassium.

[0107] Evaporation was continued to sg 1.22 and sodium chloride wasobserved. A sample of the crystallized salt was taken from the pan fromwhich much of the calcium solids had been removed for the firstanalysis. The crystals were generally small with none larger than 3 mm.

[0108] This sample was rinsed for 10 seconds with an equal weight of thestarting brine and then allowed to drain outdoors for 3 days. This wasthe only ‘washed’ sample in either run. The analysis, dry basis, was;Ca, 0.058%, Mg, 0.357%, SO₄, 0.021%, and K, 0.137%. With even thisminimum of preparation, this salt met the specifications of most statesfor deicing salts, and is suitable for soil stabilization, pond sealing,and all such uses of common salt.

[0109] For those skilled in the art of salt production, it is apparentthat, with simple washing to lower the magnesium content, this salt willmeet the American Water Works Association specifications for watersoftening. It can also be treated in a conventional manner for reducingthe calcium and magnesium to levels suitable for electrolysis to causticand chlorine.

[0110] The suitability for water softening is particularly important asthe greatest single salt use in California is for softening water forsteam assisted production of Heavy Oil. Such steam assist is used inproduction of more than 145,000,000 barrels/year, nearly half ofCalifornia on-shore oil production. The use of surfactants and emulsionsfor Enhanced Oil Recovery uses softened water to minimize surfactantuse. Increasing oil prices makes these practices more economical and therecovery of waste salts reduces costs for increased recovery.

[0111] Some of the bitterns did not evaporate to dryness even underthese hot dry conditions. This proves their value for dust control onthe dirt roads common in Southern California.

[0112] A second run using the same evaporation pans and a similarprocedure was made in late September as the nights started to cool.Analysis of the recovered salts followed the pattern of the first tests.All salt samples contained more than 90% sodium chloride without washingor separation of windblown dirt and dust. These samples are suitable forsoil stabilization and pond sealing ‘as is’ and as crude salt suitablefor refining by my U.S. Pat. No. 5,300,123 to a purity up to andincluding chemical grade sodium chloride.

[0113] One liter of the remaining brine (sg 1.342) was furtherevaporated outdoors until a level slightly above 520 ml. total of brineand settled salts was reached. Some of the precipitated salts hadadhered to the glass above the brine level and are not included in thisvolume. The brine was drained and 480 ml. was recovered at sg 1.293.Despite the evaporation of over half of the water, the precipitation ofthe salts due to temperature changes had lowered the specific gravity ofthe brine.

[0114] This 480 ml was divided into 100 ml. and 380 ml. splits. The 100ml was transferred to a 200 ml beaker, which was then sealed withplastic wrap to avoid evaporation. It was then cooled by refrigerationin a compartment at 4.4*C. The wrap was removed only for as long as ittook to measure temperature with a thermometer that was also kept in therefrigerator. The first precipitation of fine crystals was noted at14*C. Cooling was continued overnight in an iced compartment. Themorning temperature was 2.2 C. The fine precipitate had caked at about45% of the total volume. A stir spatula was used to break the cake intofine particles, which were allowed to settle. The settled level wasabout 40% of the total volume. The liquid was drained and the wet solidswere heated in a microwave oven for 3 to 5 second intervals to avoidoverheating and evaporation. At 20 seconds total heating time thecrystals had melted enough to allow temperature measurement (30.5*C) In7 minutes it dropped to 27.7*C and held. This was the apparent meltingpoint of the crystals in contact with that brine.

[0115] Brine hardness was measured using a Hack Kit 5B and the procedureused for checking brines used in water softening [9]. It was 1020 grainscalculated as calcium carbonate.

[0116] The 380 ml split was placed into a ceramic bowl, sealed with athin clinging plastic wrap, and put out to chill overnight. The airtemperature was 14*C. at midnight and 10*C. at 6:10 AM. The sampletemperature was 9.5*C. The volume had not measurably decreased so theindication is that the night low was cooler than the 6:10 AMtemperature.

[0117] The brine in the bowl remained very clear and appeared to beunchanged but, on examination, it was found to contain many crystalclear acicular crystals 4 to 6 cm. long. These were removed with astainless steel table fork, drained, weighed, and then placed on filterpaper for blotting some of the adhering brine. The blotting removed anadditional 3.5 grams of brine. The drained and blotted weight was 58.1grams and the sg of the remaining brine was 1.254 (60*F). 40 grams ofthese crystals were placed in a 125 ml sample bottle and heated in themicrowave for short increments to initiate melting. The ‘holdtemperature’ was measured, the liquid was then drained from the bottle,and a hardness measurement made on the drained liquid. Four cycles werecompleted. Each time the hold temperature was 27.7*C (81.9*F). Thehardness equivalents of the melts were 1320, 2100, 1500, and 1500respectively. This sodium sulfate containing about 2-3% of magnesium andminor amounts of other salts functions well for heat storage and thephase change point lies within the optimum range for raising chickens,for example, and also for aquaculture as in raising tilapia, forexample.

[0118] It is common knowledge that one may change the amounts of saltsin a mix with sodium sulfate in order to control the temperature atwhich the phase change occurs. For example, it is possible to lower thetemperature at which the phase change occurs down to about 65*F usingsodium chloride alone. This ability to make these mixtures is well knownto those skilled in this art. In this case the complete mix is made fromsalts recovered from wastes.

[0119] Also well known are the methods for separation of the magnesium,and other salts, from the sodium sulfate. The magnesium may be separatedby adding lime or hydrated lime. The precipitated magnesium oxide, orhydroxide, is particularly suitable for use in neutralizing minerals inacidic solutions because the precipitate settles well.

[0120] For example, (Reference—Bureau of Mines Report of InvestigationsNo. 9023; “Reclaiming Heavy Metals From Waste water Using MagnesiumOxide”.) when minerals were precipitated with magnesium oxide preparedby calcining magnesium hydroxide, the settled volume of the precipitatewas only ¼ of the volume of precipitates from using calcium oxide orcalcium hydroxide.

[0121] Sodium Sulfate for Heat Storage

[0122] Sodium sulfate deca-hydrate is the most widely studied materialfor storing phase change energy because it is effective at temperatureswithin our daily experience, say from refrigeration at 4*C. to warmwater at 31*C.

[0123] Uses extend from filling water bottles to keep ones feet warm toheating entire living and working spaces.

[0124] It is possible to produce sodium sulfate recovered fromirrigation drainage and similar salty wastewaters, to the puritycommonly used for heat storage and energy conservation. Additionally, Ihave found that it is not necessary to have the high purity sodiumsulfate used by others for energy storage.

[0125] I have found usable heat storage properties in mixed salts asrecovered from irrigation drainage by evaporation. I have found otherusable mixes where these salts are only partially separated by the useof ambient cooling and/or heating, and no fossil energy is requiredother than that used for materials size control, handling and transport.

[0126] Uses extend from filling water bottles to keep ones feet warm, toheating entire living and working spaces, and, using the phase change at241*C., even for refrigeration according to the cycle used forrefrigeration by burning propane.

[0127] These low cost salts are ideally suited for massive energystorage for agricultural uses. It is well known that different plantsand animals grow best at some discrete range of temperature suited totheir species.

[0128] An abundance of low cost sodium sulfate allows the use of storedsolar heat to heat living space of plants and animals at night. It alsoallows the use of nighttime coolness to be stored for use in coolingliving space in the daytime for plants, animals, and for humans.

[0129] Pure anhydrous sodium sulfate also undergoes a phase change at241*C. (465*F) with the absorption of 27 BTU/lb (15 cal./gm.) ofmaterial. I have found that considerable amounts of other salts may betolerated while retaining much of the value for heat storage.

[0130] Using pellets of the anhydrous material recovered from wastesmakes it more economical to store solar energy or to transfer wasteheat, from flue gases for example, at that very usable 241*C. Storage ofheat at this temperature is suitable for refrigeration.

[0131] Thus it is demonstrated that heat storage products of greatutility can be prepared using materials recovered from common wastes,and with a minimum expenditure of energy for processing.

[0132] More Experimentation—Irrigation Drainage from Central San JoaquinValley

[0133] Irrigation drainage from the San Joaquin Valley of Californiacontaining about 0.8% Total Dissolved Solids (TDS) was evaporated in atest pan. The first separations observed were limestone precipitatesfloating on the surface. Evaporation was continued from the startingdepth of 3.25 Inches to 0.5 inches. The solids were separated bygravity, placed in a closed container along with enough of the remainingbrine to keep them well submerged, and stored outdoors from Jul. 2, 2000until Apr. 3, 2001. This would correspond with pond storage from earlyin an evaporation season until the end of a winters harvest period.

[0134] After separation and washing in water (20 ppm max. TDS), theagglomerations were broken by rubbing between the fingers. Dryingproduces more agglomerates and these were again broken by rubbingbetween the fingers and then screened.

[0135] The size was 97% through a 20-mesh screen, 84.8% through a60-mesh screen, and 60.5% through a 100-mesh screen. This meets thetypical specifications for agricultural limestone (State ofPennsylvania) (1) for agricultural limestone of 95% through a 20 meshscreen, 60% through a 60 mesh screen, 50% through a 100 mesh screenwithout the expensive and energy intensive mining and grinding of commonpractice.

[0136] The sample was then titrated with normal hydrochloric acid andthe alkalinity was determined to be the equivalent of theoreticallyobtainable calcium carbonate.

[0137] This calcium carbonate recovered from irrigation drainage andsimilar waste waters can be used for all the usual types of acidneutralization including mine drainage, streams with low pH water due toacid rain, and for desulphurization of the flue gases from sulfurcontaining fuels.

[0138] Still More Experimentation—Drainage from Southern San JoaquinValley

[0139] Salt samples and a residual brine sample were taken directly fromone of several solar evaporation ponds totaling about 80 acres. Beforebeing shut down, the ponds had been used for about 15 years to evaporateirrigation drainage. Mitigation requires salts removal and landreclamation.

[0140] Analysis of five (5) previous samples of salts from these ponds,as provided by California Dept. Of Water Resources (DWR), show sulfateion contents of about 2/3 of all ions in the analysis, other than water.Analysis of one sample was approximately 85% sodium sulfate, 11% calciumsulfate, 2% magnesium sulfate, 1.6% sodium chloride with 0.6% aspotassium and boron compounds (dry basis).

[0141] It is presumed that rainfall leached much of the sodium chloridefrom the salts after the ponds were drained.

[0142] A sample was dissolved to make a saturated brine. The brine waschilled to 38*F, well within the range reached by outdoor spray chillingin winter.

[0143] The crystallized hydrates were found to have a phase change fromhydrate to melt at 82*F, just as did the hydrates recovered from theSalton Sea by solar evaporation and chilling outdoors.

[0144] A sample of the residual brine from that pond was chilled tobelow 32*F without crystallizing any hydrates. On chilling to below22*F, there was some precipitation of what is believed to be sodiumdi-hydrite, a compound known to form from sodium chloride brine at 22*F.

[0145] This remnant brine is very suitable for dust control and even foruse as a liquid for heat transfer in refrigeration, and, after loweringof the sodium by evaporative crystallization, or chilling, is valuablefor return to the soil to provide the calcium and magnesium needed asplant nutrients and for soil modification.

[0146] Sodium Sulfate for Modification of Properties of Soils

[0147] The crude sodium sulfate type salts perform well for pond sealingand for soil solidification, and for resistance to erosion by wind andwater.

[0148] Lime stabilization of soils is a common practice: lime takes upwater forming calcium hydroxide which reacts by dissolving silica fromthe soil and forming bonds of calcium silicates. It has been shown thatthe rate of the formation of silicate bonds is greatly accelerated bythe inclusion of sodium chloride with the lime and the use of wastesodium chloride was suggested for this purpose. (Am Soc. Civil Eng.references.)

[0149] I have found that the inclusion of sodium sulfate, along with orin place of, the sodium chloride added in that practice, immediatelystarts to produce sodium hydroxide and gives a much faster increase therate of formation of the binding silicates. Further, the lime-sodiumsulfate reaction produces gypsum that sets quickly. This early strengthassists in reducing the breaking of the silicate bonds during the “curetime” before the silicate bonds are developed enough to resist suchbreakage. The gypsum sands of Daytona Beach are a well-known example ofgypsum in a driving surface.

[0150] In soil solidification, the entire spectrum of needs can besupplied from products derived from waste irrigation drainage.

[0151] A—the calcium carbonate is separated during evaporation andcalcined to form the required lime.

[0152] B—the irrigation drainage can be used as compaction water alongwith the lime and salts,

[0153] C—the irrigation water can be partially evaporated to increasethe amount of salts in the compaction water,

[0154] D—the crude salt mix can be used “as is” or dissolved in thewaste water used for compaction,

[0155] E—after concentration by evaporation, or after dissolving thecrude salts, chilling the solution selectively crystallizes sulfates (ascomplex hydrates of magnesium and sodium sulfate) and the percentage ofsodium chloride in the remaining liquid is increased.

[0156] Sodium Sulfate for Control of the Phymatotrichum omnivorum

[0157] This fungus attacks the roots of Dicots, the more notable beingalfalfa, cotton, and citrus. Common names are “Cotton Root Rot” and“Texas Root Rot”. The first task given (1886) to Texas AgriculturalExperiment Station was to find a way to combat this root rot.

[0158] The incidence of root rot from East Texas to Indio, Calif., andfrom Los Vegas, Nev. south into Sinaloa, Mexico, impairs or totallyruins the productivity of millions of hectares of land that can berestored to production

[0159] In the late 1960's Lyda found this to be caused by an excess ofcalcium carbonate where sodium ion is deficient. These soils do notswell enough to allow escape of carbon dioxide from decay of soil humus.The fungus requires more than about 3% CO₂ to start growth. Lyda usedsodium chloride to add enough sodium ion increase soil swelling and aresultant increase in soil permeability to gases. This cured the rootrot but the byproduct is calcium chloride which must drain for thedesired plant growth. This drainage increases the chlorides in thegroundwater and this practice is little used.

[0160] Sodium ions from sodium sulfate also increase soil swelling withthe formation of a desirable product, gypsum, instead of the undesirablecalcium chloride.

[0161] Further, the chloride content of sodium sulfate produced fromirrigation waste waters can be reduced to a tolerable limit and themagnesium content, not tolerable in commercial sodium sulfate, is anecessary plant nutrient. Alfalfa suffers greatly from root rot butrequires relatively large amounts of magnesium as a nutrient.

[0162] I have discovered that a cure for root rot results fromsimultaneous addition of magnesium sulfate nutrient in a completelysoluble form as nutrients for soil amendments. Moreover, the magnesiumand sulfates can be obtained through the purification of waste waters.

[0163] Sodium Sulfate for Water Softening

[0164] In the investigation of the possible uses of sodium sulfaterecovered from wastes, I found an unusual and unexpected use in therecycling of water softening waste brines and oil field produced waters.

[0165] The addition of sodium carbonate for precipitation of bothcalcium and magnesium as carbonates is well known. But the precipitatesare fine and will not settle leading to a need to provide seed crystalsto get a settled product. The amount of handling has kept this practicefrom being adopted commercially.

[0166] The removal of calcium from brine by addition of sodiumcarbonate, and followed by the precipitation of magnesium with sodiumhydroxide is well known. The large flakes of magnesium hydroxide aid insettling out the fine calcium carbonate. But this is effective for onlythe more dilute solutions. It has been demonstrated that, the hardnesscontent of the spent brine must be limited to about 1000 grains, 17,000ppm, or this floc will not settle to more than about 30% solids as theprecipitates do not settle to a dense floc. Again, drying for disposal,and disposal itself, is very costly. Thus it would be ecologicallydesirable to have a means for reclaiming the spent brine from ionexchange processes whereby the wastes were more easily disposed of, andeven more desirable to have a saleable product.

[0167] I have found that when sulfate ion is added to the waste watersoftener brine, the gypsum formed settles very well and can be separatedand washed to make a fine grained gypsum superior to mined gypsum inpurity and in reactivity. The material color is light and bright andsuitable for paper filler, filler for molded plastic items, and othersimilar uses.

[0168] Sodium sulfate is a good supply of the sulfate ion as it includesthe sodium ion as a direct replacement for the calcium and in the exactamount needed for regenerating the softener resin of zeolite.

Ca Cl₂+Na₂ SO₄+2H₂O→2 NaCl+CaSO₄.2H₂O

[0169] Commercial grades of sodium sulfate are typically of high purity,99+% sodium sulfate and low sodium chloride, typically 0.5 max NaCl.This product works very well in precipitating calcium but is costly dueto the amount of energy used in separation and purification.

[0170] Sodium sulfate recovered from waste is suitable even when thesodium chloride is too high to met the usual commercial standards. Thepresence of sodium chloride in the sodium sulfate to be used for watersoftening is acceptable because sodium chloride is required for makeupof the regenerative solution. Where the water being softened is intendedfor applications other than potable water, say for industrialapplications like cooling towers and once through boilers, the use of aless pure sodium sulfate derived from waste waters gives significantsavings.

[0171] After settling of the gypsum, the magnesium is removed byprecipitation and, after washing to remove the brine, the precipitatedmagnesium carbonate, or magnesium hydroxide, is suitable for use in manyof the usual applications of magnesium carbonate, or magnesium hydroxideand/or, following calcination, as magnesium oxide.

[0172] Reclamation of domestic sewage for industrial use and forirrigating non-food plants is becoming increasingly important.Organizations such as California Water Reuse Association and many othersnote that domestic water softeners that use salt added at the home addsodium chloride brine to the sewers.

[0173] Unwanted influences of sodium towards plant growth may be largelyoffset by additions of calcium. However, there is no presently knownmethod for offsetting the effect of the chloride ion. Further, thesulfate ion content may be lowered by well methods commonly used inwater treatment while no such cost-effective methods are known forchloride ion. Thus, the substitution of a plant nutrient ion, such asthe sulfate ion, for the harmful chloride ion, would be of benefit tothe reuse of domestic sewage waters in irrigating plants.

[0174] I have found that it is possible to substitute commercial gradesof sodium sulfate for the commercial grades of sodium chlorideordinarily used in sodium ion exchange water softening and therebyreduce the chloride ion in the waste brine down to the level that existsas an impurity in the sodium sulfate and water used for the regeneratingbrine.

[0175] Ordinarily the sulfate ion content in sodium chloride used forregeneration of ion-exchange softeners is limited. For example, theSpecifications of American Water Works Association (AWWA) limit thesulfate ion content in the salt to a maximum of 1.4%, which, in asaturated brine of 26% salt, calculates to a maximum of 0.346% sulfateion in the regeneration brine.

[0176] I have found that in using sodium sulfate regenerating brine,sulfate ion contents up to about 5% in the regenerating brine may beused for regeneration of resins and other media used in sodium ionexchange water softeners.

[0177] In this manner, the increase in chloride ion content is largelyeliminated and the substituted sulfate ion is of beneficial use as aplant nutrient.

[0178] I have also found that sodium sulfate of the same usability forsodium ion exchange water softening as the above-mentioned commercialgrades, can be produced from waste irrigation waters.

[0179] Salt for Rural Sanitation

[0180] A sample of the salt recovered from the Salton Sea was used tomake a solution containing about 1% sodium chloride. This solution wasused to make a weak, less than 1% chlorine, sodium hypochlorite bleachaccording to the method of Grott. Though undesirable impurities likeboron are present, the percentages are so reduced according to the 2-5ppm use of the chlorine in the bleach that using it for sanitation ofwater for cleaning of home surfaces, eating and cooking utensils,clothes and bedding is safe.

[0181] Do-It-Yourself Liquid Chlorine Bleach for Rural Sanitation

[0182] Much of the world's population depends on boiling to produce safedrinking water but the first utensil dipped into the cooled water mayre-contaminate it, and the water will no longer be “safe to drink”.Solar heat and other practices may also be used for killing parasitesand germs but the problem of recontamination remains. Chlorine is theonly practical means for extending the period of safety of the drinkingwater.

[0183] Many plants and vegetables must be cooked to prevent illness whenthey could be made safe to eat simply by washing with chlorinated water.Just like the drinking water, cooked foods, after cooling, can berecontaminated by use of serving utensils that were not sanitized.

[0184] In many places in Kenya, except for a few trees left for shade,the plains and hills have been stripped of trees and shrubs and woodmust be carried for long distances.

[0185] Chlorine is a common agent for sanitizing water and residualchlorine adds a measure of lasting protection to the treated water.(Note of caution: chlorine does not kill parasites). Liquid chlorinebleach, sodium hypochlorite, is one material common in home use forsupplying active chlorine.

[0186] Handling dilute bleach, even with chlorine concentrations below1%, requires caution, eye protection is advised, and drinking the bleachitself is very dangerous. Use of bleach in sanitizing water containingorganic materials is reported to increase the risk of cancer in humansby up to 10 chances per million.

[0187] The objective is to have equipment and operations requiringskills comparable with those of bicycle and auto mechanics, and to usecommonly available materials to the full extent possible. Celldimensions were matched to the capabilities of a 12-volt car battery.Sodium hypochlorite forms when salt water is electrolyzed using DirectCurrent (DC). The theoretical voltage drop across a single cell is below3 volts but in operation it is about 3.3 to 4.0 volts depending onresistance losses in the wires and electrodes, the salt concentrationand temperature of the solution, and the spacing of the electrodes. The10-12 volt drop for a 3-cell electrolysis unit fits well with the 12volt D.C. battery typically used in cars.

[0188] Car batteries are charged (recharged) using a source of DC powerat about 14 volts. Battery chargers converting AC to DC are common, andthere are also solar cell chargers. For a true “do-it-yourself” powerunit we chose to use a car alternator, or generator, and to drive it bya Vee belt using the driving wheel on a bicycle. The rate of rotation ofthe bicycle wheel is matched to the characteristics of a particularalternator or generator. A typical alternator from a mid-sized Americancar will produce about 7 amperes at 1500 revolutions per minute (rpm)and the power output increases as the rpm are increased. The size of thepulley used on the alternator is chosen to meet the preference of thebicycler to produce the necessary 1500-2000 rpm. Charging to maintainbattery capacity is usually carried out during the bleach making so asto avoid drawing the battery down below the full 12 volts operatingcapability.

[0189] Alternators required voltage regulation. They may have a built-involtage regulator or they may require a separate one and it is necessaryto know which design of alternator is being used. Generators require aseparate voltage regulator. We find that producing the 7-10 amps at 14volts common for battery chargers is well within the comfort range foreven lightly built teenagers. They report that producing a chargeroutput of 7-10 amperes feels comparable to pumping a bicycle on levelpavement at about 12-15 miles per hour. Geared bicycle drives allowadjusting the pedaling rpm to an individual's comfort range. In the USA,the cost for all components, including a rebuilt alternator, a voltageregulator, Vee belt, and used bicycle components is on the order of$100-$150 per charging unit.

[0190] This “first generation” cell will serve to get the programstarted. Ingenuity and feedback from practitioners and interestedvolunteers will bring forth improvements and adaptations to better fitvarious local conditions. Full success of the program depends on theseideas from the field.

[0191] Graphite and/or titanium were chosen for the electrodes becauseof their known properties, availability, and acceptable costs.Commercial electrolysis units commonly use plated titanium to allow longuse before maintenance or replacement is required. This extra expensefor coating is not cost effective where labor costs are low and there isa need to minimize the cost of imports.

[0192] An assembly of four electrodes is clamped with the facesparallel. Plastic strips that do not conduct electricity, and about 2.5wide×7.5 cm long×6 mm thick, are placed at the top of the electrodeassembly to provide a 6 mm spacing between electrodes. A 3-cell unitwith a voltage drop of 10-12 volts is formed by clamping 4 electrodeswith faces parallel, and with a 6 mm spacing between the faces, as shownin the photo. Power is supplied only to the outside electrodes with thetwo inner electrodes providing two working surfaces each. If a coatingforms on the electrodes, reversing the wires cleans the electrodes.

[0193] Electrode dimensions of 7.5 cm×15 cm were chosen to fit the poweroutput ranges of different size batteries. For this assembly, theamperage required by the cell can be adjusted by the depth of immersionof the electrodes. Immersion to 7.5 cm in a 1% salt solution typicallydraws 9-11 amperes. Of course, changing the salt content of the solutionalso changes the electric characteristics of the system.

[0194] The container can be any glass or plastic. A 2-liter plastic softdrink bottle works well. A working capacity of about 1.5 liters isavailable when the bottle top is cut off just above the label. Activechlorine produced depends on the power source, the strength of the saltsolution, and the electrode area submerged, as well as the length of thetime period during which power is applied to the cell. The hourlychlorine production can be varied within the range of 600 parts permillion (PPM) to 6000 PPM. Even the lower concentration is enough tosanitize and protect several hundred liters of drinking water.Experience with this simple unit has demonstrated that making usablesolutions of bleach is well within the capability of persons havingcommonly available skills.

[0195] “Do-It-Yourself” liquid chlorine bleach for sanitizing and/orprotecting drinking water is made using salt, cells costing about $20.00in US, and 12 Volt DC electric power from a car battery. Recharging maybe by a battery charger, or solar cells, or a car alternator belt-drivenby a bicycle wheel.

[0196] In the USA, household bleach is sold and used at strength of 5.5%chlorine. It is used by a great many people of all educational levels,in large quantities, and one rarely hears of accidents damaging to usersor their children. The bleach generated in the cells described herein isusually only a tenth to a hundredth of this strength.

[0197] For use in sanitizing water, instrumentation for testing forresidual chlorine is of great help. In the absence of suchinstrumentation and skills, another way is available. The US Navy hasused bleach on ships for many years and much information is available onthe Internet. For water sanitation, one typically adds so many drops ofbleach to a gallon of water, waits 30 minutes, and smells the water. Ifthe bleach is detectable by smell, then there is enough residualchlorine that bacteria in the water were killed. (But not parasiteswhich must be filtered out or killed by pasteurization or boiling.) Ifthe smell is too strong, dilute the treated water by a measured amount,mix, wait 30 minutes, and try the smell again. If there is no chlorinesmell, add another measured amount of the bleach, mix, wait another 30minutes, and smell again.

[0198] This trial procedure establishes a safe level by experiencewithout the use of instrumentation or test kits, and even when theinitial strength of the bleach is not known. It is tedious and boring atany time and can be very irritating if one is thirsty, but it works.When, after that 30-minute wait period, the residual chlorine isdetected by smell, then there is enough residual chlorine to give all ofthe benefits possible.

[0199] For removal of parasites, building and using slow sand filtrationunits is well within the skills of at least some inhabitants of mostvillages. Demonstrating and teaching slow sand filtration presents afurther opportunity for “teaching a person to fish”.

[0200] “Do-It-Yourself” bleach making offers an opportunity to personswho want to have more control over their health. Success with increasingthe safety of their drinking water will give them an accomplishment ofwhich they can be proud and the success will increase their desire andskills for learning more about how to help themselves.

[0201] Caustic Soda from Slacked Lime and Sodium Sulfate

[0202] Ca (OH)₂ solids of low solubility+(Na₂SO₄) in solution a 2NaOH+CaSO₄ solids of low solubility. Alternately, the sodium sulfate canbe as the decahydrate.

[0203] Caustic is produced primarily as a co-product with chlorine byelectrolysis of sodium chloride. Recent prices of caustic are very highbecause of reduced demand for chlorine. Further, there are environmentalpressures to further reduce the use of chlorine. It would beadvantageous to have a supply of caustic independent of the demand forchlorine.

[0204] The reaction of slaked lime with sodium sulfate to form causticsoda and calcium sulfate is well known but is rarely practiced becauseof low yield and the weak solutions of caustic that are formed.

[0205] I have found that the yield and rate of reaction may besignificantly increased by using extreme abrasive and grinding pressuresto remove the coating of calcium sulfate that forms on the lime toreduce reaction rates and decrease yields.

[0206] Further, the concentration of the caustic soda is increased andun-reacted sodium sulfate is crystallized by evaporation of thesolution, and recycled. In a second instance the evaporation is by solarevaporation.

[0207] Having described the invention in such terms as to enable oneskilled in the art to make and use it and having identified thepresently best mode of practicing it,

I claim:
 1. A method using an aqueous effluent comprising the steps of:collecting water contaminated with the 0.15% or more by weight of thesalts of Na, Ca, Mg, Cl, SO₄, or CO₃ or combinations thereof; processingthe contaminated water to produce a first effluent of clean water and asecond effluent of waste water; analyzing the clean water to determineif its sodium content is too high for potable use; and using the cleanwater for laundry applications if it has been determined that its sodiumcontent is too high for potable use.
 2. The method of using an aqueouseffluent of claim 1 wherein the step of processing the contaminatedwater includes the step of water softening.
 3. The method of using anaqueous effluent of claim 2 wherein the step of processing thecontaminated water is by ion-exchange, precipitation, membrane softeningor electrolysis.
 4. A method using an aqueous effluent comprising thesteps of: collecting water contaminated with the salts of Na, Ca, Mg,Cl, SO₄, or CO₃; processing the contaminated water to produce a firsteffluent of clean water and a second effluent of waste water; analyzingthe clean water to determine if its sodium content is too high forpotable use; and using the clean water within a cooling tower todissipate heat if it has been determined that the clean water's sodiumcontent is too high for potable use.
 5. The method of using an aqueouseffluent of claim 4 wherein the step of processing the contaminatedwater includes the step of water softening.
 6. The method of using anaqueous effluent of claim 5 wherein the step of processing thecontaminated water is by ion-exchange, precipitation, membrane softeningor electrolysis.
 7. A method for deicing and reducing the formation ofice on roads comprising the steps of: collecting water contaminated withthe 0.15% or more by weight of the salts of Na, Ca, Mg, Cl, SO₄, or CO₃or combinations thereof; processing the contaminated water to produce afirst effluent of clean water and a second effluent of waste water;processing the second effluent of waste water to produce a substantiallysolid salt mixture; and applying the solid mixture of salts to a roadfor deicing or the reduction of the formation of road ice.
 8. A methodfor deicing and reducing the formation of ice on roads of claim 21wherein the step of processing said second effluent of waste water tocreate a substantially solid salt mixture includes the step ofevaporation.
 9. A method for deicing and reducing the formation of iceon roads of claim 21 wherein the solid salt mixture includes 90% or moreof sodium salts.
 10. A method for deicing and reducing the formation ofice on roads of claim 22 wherein the solid salt mixture includes 90% ormore of sodium salts.
 11. A method for deicing and reducing theformation of ice on roads comprising the steps of: collecting watercontaminated with the 0.15% or more by weight of the salts of Na, Ca,Mg, Cl, SO₄, or CO₃ or combinations thereof; processing the contaminatedwater to produce a first effluent of clean water and a second effluentof waste water; processing the second effluent of waste water to producea concentrated solution of salts; and applying the concentrated solutionof salts to a road for deicing or for reducing of the formation of iceon the road.
 12. A method for deicing and reducing the formation of iceon roads of claim 25 wherein the step of processing said second effluentof waste water to create a concentrated solution of salts includes thestep of evaporation.
 13. A method for deicing and reducing the formationof ice on roads of claim 25 wherein the concentrated solution of saltsinclude increased levels of calcium and magnesium salts.
 14. A methodfor deicing and reducing the formation of ice on roads of claim 26wherein the concentrated solution of salts include increased levels ofcalcium and magnesium salts.